Bulk freeze-drying apparatus

ABSTRACT

The invention refers to an apparatus for freeze-drying foodstuffs, luxuries and victuals in a chamber adapted to be closed by means of vacuum and while heating with a plurality of vertical, fixed heating devices. The chamber includes a plurality of movable vertical receptacles (for receiving the material to be dried) alternately arranged with the heating devices and capable of transporting the material longitudinally through the chamber between the heating devices.

451 Apr. 24, 1973 BULK FREEZE-DRYING APPARATUS 2,853,796 9/1958 Sanders..r.................t................34/5

Gunter A. H. Wehrmann, Nibelun- FOREIGN PATENTS OR APPLICATIONS Inventor:

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UNITED STATES PATENTS chamber includes 'a plurality of movable vertical receptacles (for receiving the material to be dried) alternately arranged with the heating devices and capable of transporting the material longitudinally through 34/5 the chamber between the heating devices.

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BULK FREEZE-DRYING APPARATUS BACKGROUND OF THE INVENTION It is known to build freeze-drying systems by arranging containers that receive the material to be treated in the vacuum chamber in alternate arrangement with the heating apparatus, the material being transported through the chamber. There are used at the same time relatively flat pans filled with the material. These pans rest on heating plates arranged in the chamber in horizontal plane, the pans being moved on the heating plates longitudinally through the chamber at the rhythm of the treating operation. The pan-like containers whose walls can be ribbed respectively receive a comparatively small volume of the material to be dried.

I Accordingly the chamber has to be loaded with a plurality of pans. In view oftheir great quantity, the mechanical arrangement of the pans in the carrier platforms of the chamber and also the mechanical discharge of the pans is associated with difficulties and circumstantial conditions. The filling and unloading operation requires for mechanization an expensive and complicated working apparatus. In addition, the accomodation of the horizontally positioned pans in the chamber does not permit at all to make the best use of space, for between the horizontally positioned pans and the heating plate arranged over it, it is not possible to leave less than a relatively large minimum distance if a perfect removal of steam is to be ensured. There is also the danger that the comparatively flat pans cannot be entirely emptied with the required promptness, and thus losses of material must be expected. To obtain a continuous mode of operation the use of movable carriages is proposed. Each carriage has in several levels horizontally positioned carrier plates that are also made adapted to be heated. The heating is electric, the carriage being provided with a sliding contact. It is further known to transport the material gradually on a conveyor belt that extends longitudinally to the tunnellike chamber. Inside the conveyor apparatus there is a heating device. The work accomplished by such a freeze-drying system is limited.

Also known are freeze-drying systems where the use of space in the vacuum chamber has been improved. The spaces in the receptacle that receives the material extend in a vertical direction. There has been provided a carriage that can be moved longitudinally to the chamber. The receptacle is connected with the chassis of the carriage and in this receptacle the heating devices are firmly mounted. These heating devices extend, for instance, in the form ofa winding line in a vertical plane. The horizontally running pipes of the heating device are covered toward the top and toward the sides. The space formed thereby is open at the bottom. The coils of pipe viewed in front elevation are provided in staggered position to each other. The spaces, between the coils of pipe which have roof shaped coverings on top serve to receive the material. The whole receptacle, the plurality of heating devices and the chassis of the carriage form a structural unit that can be inserted into the chamber. The large receptacle that rests upon the carriage and has multiple subdivisions which are conditioned by the heating device can be quickly filled with the material. The whole chassis will then move into the vacuum chamber. The heating apparatus is then connected by means of an airtight quick coupling to the circuit of heating medium that feeds the chamber. The lateral spaces that remain free between the loading-unit and the cylindrical crsssection of the chamber can be used by mounting capacitors. The operation is a charging operation where respectively one or two receptacle units are introduced in the chamber. The loading and unloading can be carried out in a mechanized manner. The essential obstacle of a semi-continuous operation of such a carriage chassis with built-in heating apparatus is that the supply pipes for the heating medium must be reliably moved through the chamber tunnel under high vacuum. Another problem is to ensure the tightness of the couplings. No impurities can penetrate into the vacuum space.

The problem to be solved by the invention is to provide a freeze-drying apparatus in which on the one hand the space of the chamber cross-section can be thoroughly used and on the other, the loading and unloading can be mechanically carried out, eliminating at the same'time the danger of leakages in the supply pipes.

SUMMARY OF THE INVENTION This invention is directed to a freeze-drying system characterized by the fact that by arranging the receptacles for the material and the heating apparatus in vertical direction, the heating devices that extend in the vertical longitudinal plane of the chamber are firmly mounted in the chamber and the receptacles can be separately transported between the stationary'heating devices.

In this manner a combination of advantages in one and the same freeze-drying apparatus is obtained without the disadvantages of the known systems. The receptacles that receive the material are pockets of predetermined width that extend in vertical direction. They can be quickly and perfectly filled with the material. They can also be mechanically emptied since it is possible to let the material fall downwardly at the desired moment. The heating devices are constantly firmly connected with the supply pipes and the joints. No coupling of the pipes is necessary for connection with the stationary supply after the receptacles are inserted into the chamber and when they are moved out. Thereby the danger of formation of leakages is overcome. The movable receptacles can be passed'comparatively tightly on both sides on the stationary heating devices. The space that remains between the heatingcoil permits a linear and unobstructed removal of the steams in the verticals. By means of the ventilators mounted on the side walls of the pockets or with openings covered with screen-like metal webs the steam can be separated from the material in horizontal direction'in theshortest way and be removed by suction in vertical direction. The quick, unobstructed removal of the steam from the chamber increases the efficiency of the system by saving time. In addition, the vertical arrangement of the product pockets represents a good use of space of the cylindrical vacuum chamber, the height of each pocket being greater than the width. The capacity and efficiency of the freeze-drying system can be substantiallyincreased. The effect of the drying is intensified. Combined with this the loading and unloading of the receptacles that receive the material can be mechanically designed without great cost and thus a considerable economy is also obtained in this sense.

Several receptacles are conveniently combined as vertically extending pockets into a movable structural unit that can be moved between the stationary heating devices. At the same time the vertical pockets can be pendently mounted on a carriage movable above the heating devices. Such a design is simple to make and not costly. Besides, the pendent arrangement of the product pockets makes possible a good use of the space between the heating devices that extend in a vertical plane. The tolerances can be kept relatively small.

The side walls of the pockets can have perforations but in such a manner that the falling out of the material is prevented. The bottom of the pockets can be downwardly open and can be made, for instance, as traps.

All the pockets present in the width of the chamber can be combined to form a movable structural unit. But it is also possible to combine a small number of pockets to form a movable unit. It is further possible that each vertical pocket be individually moved through the chamber. In this case the pocket is conveniently guided by a rail or the like arranged at the bottom of the chamber in longitudinal direction and in the same manner in the upper area of the chamber.

The freeze-drying apparatus is suited for any food material or the like that can be poured and not only for a granulated or powdered material such as coffee or tea granulate but also for piece products, provided the pieces are smaller than the width of the pockets as for example, vegetables, fruits, meat.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a cross-section of the vacuum chamber with the arrangement according to the invention of the receptacles and heating devices in diagrammatic manner.

FIG. 2 represents a detail of the apparatus of FIG. 1 in large scale.

FIG. 3 illustrates still another embodiment diagrammatically and graphically,

FIG. 4 shows a detail of point IV of the embodiment of FIG. 3 in elevation.

In FIG. 5 is diagrammatically illustrated in plan view the vacuum chamber with another embodiment for the movable receptacles.

In FIG. 6 is diagrammatically illustrated another embodiment for the movable receptacles.

DESCRIPTION OF THE PREFERRED EMBODIMENT can be firmly arranged on the brackets 5 of the walls of the'chamber. The common feed pipe 6 is passed at a suitable point through the walls of chamber 1. The

receptacle 7 that receives the material has a plurality of vertically extending pockets 8 that are firmly mounted in an upper portion 9 of the receptacle or form therewith a structural unit. The receptacle 7 is provided at the sides with rollers that run on rails 11 that are supported by brackets l2 mounted on the internal side of the walls of the chamber. By means of the rails the receptacles of the material can be guided with relative accuracy and in suspension. The pockets 8 that extend in the vertical plane, when the receptacle 7 is in operation in the longitudinal direction of the chamber, in a comb-like manner pass through the intermediate spaces between the stationarily arranged heating devices 3. In the side walls of the pocket 8 there are ventilator openings 13 that consist of partially punched out blades that are oriented outwardly and diagonally upward. The size of the ventilator openings 13 and of the blades 13a depends on the size or fineness of the material to be freezedried. The heating device 3, a heating coil for instance, that extends in the vertical plane can be surrounded by a protective covering 14. Between the covering 14 and the chamber wall 8a a certain free space is provided so that the chamber wall 8b cannot rub against the heating device 3 or the protective covering 14. The receptacle 7 that has the disposable width of the cylindrical chamber 1 can be shut off toward the top by a lid 16 or several adjacent lid portions. But it is possible also to open the receptacle 7 toward the top. The bottoms 17 of each pocket are advantageously made so that they can be downwardly open. It is possible to provide a bottom lock that can be controlled by tension springs suspended from knee joints. This can be done for instance by means of an apparatus by which all the bottom locks can be opened or closed at once. The same can be said ofa lid in the upper side of the receptacle 7. The receptacles 7 that have the vertical pockets 8 can be successively introduced in the vacuum chamber 1. At the end of the cylindrical vacuum chamber that can have a length of many meters, the receptacle is taken out from the chamber with the freeze-dried material that is ready while at the beginning of the chamber a receptacle already filled is introduced into the chamber 1, the pockets 8 gripping in a comb-like manner between the heating devices 3. In the embodiment of FIGS; 3 and 4 where for the sake of brevity only a heating device 3 arranged in a vertical plane is shown, the arrangement is such that each pocket 8a that receives the material forms by itself a movable unit. The pockets extend between an upper rail 18 and a lower rail 19. At the same time the pockets 8a can rest on the needles 20 mounted in the rails 19 and be moved with little friction along the rails 18. The heating coil 3 is fastened to perpendicularly extending supports 21 that in turn can be supported on the bars 22 and 23. Between the heating devices 3 that are guided in the vertical plane there are the movable pockets 8a as independent material receptacles. The mounting on the rails 18 and 19 gives the pockets a perfect direction and guidance. The pockets 8a are provided in the same manner on the side walls with vents.

A plurality of temperature zones 24, 25, 26, as in FIG. 5 can be accommodated in the cylindrical vacuum chamber 1. For each temperature zone, firmly mounted heating devices 3a, 3b, 3c are arranged side by-side in adequate number cross-sectionally in chamber 1, the heating devices proper being surrounded by casings 14 such as plates or the like. At the same time perpendicularly standing plate-like heating devices result. The pockets 8 or 8a are moved through the free spaces between the heating devices. For the intake or delivery of a temperature zone to the other, the heating devices 3a, 3b, 3c can be provided at the front and rear ends with baffle plates 27 that run in the form of a wedge seen in section and this ensures a perfect insertion of the comb-like cross-section of the receptacle 7 or of the individual pockets 8a. The individual pockets 8a can at the same time be built with rollers 28, as shown in FIG. 6, on the narrow front surfaces, said rollers being pivotally mounted around a vertical axis. The diameter of the rollers 28 is somewhat larger than the width of the pockets 8a and corresponds to the distance between the fairing plates 14 of the heating devices 3. Thereby the pockets 8a can be comfortably moved through the heating devices 3. At the same time the pockets 8a can be combined at the upper end by a common cross-bar to form a single receptacle structural unit. The pockets 8a are gradually moved from temperature zone to temperature zone in the adequately long chamber 1 and after taking out a group of pockets 8a at the beginning of the chamber 1, a group of pockets 8a filled with fresh material is inserted in the chamber. Thereby results the semi-continuous mode of operation.

The vertically extending pockets 8, 811 can have on the lateral surfaces ventilator openings that are covered by a meshed web. The side walls of the pockets can also consist totally of a screen-like metal web, it being possible to mount the meshed web on a latticed supporting construction made of metal plate or the like and that represents the framework of the pocket.

The vertical pockets that receive the material can respectively extend over the whole disposable height of the cross-section of the vacuum chamber. But it is also possible to make a transversal space in the direction of the height in such a manner that the pockets of correspondingly less height can be moved longitudinally in the chamber on carriages arranged in different levels. At the same time the heating devices that run in the vertical plane must also be divided according to the height. instead of a suspended arrangement of the pockets, a carriage that runs on the rails can also be provided in the lower portion of the cross-section of the chamber, the pockets that receive the material being arranged upright. For special purposes it is possible to pass the pockets together with the carriage or the individually movable pockets in a diagonal angle through the vacuum chamber, not ruling out the possibility of also moving the pockets through the chamber in a horizontal position between suitably arranged heating devices. The inlet and outlet openings for the pockets remain hereon the narrow sides, wherefore the advantage of quick filling and emptying of the pockets by setting them up in vertical direction outside the chamber remains ensured.

The condensers for precipitating the steam are conveniently below the chamber. This affords a more favorable manner of removing the steams.

The heating devices can be heated by means of steam, heated liquids or ases, or also electrically.

h1le the foregoing as illustrated and described what is now contemplated to be the best mode of carrying out the invention, the constructions are, of course, subject to modification without departing from the spirit and scope of the invention. Therefore, it is not desired to restrict the invention to the particular forms of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

What is claimed:

1. A vacuum freeze-drying apparatus for particulate food material comprising a cylindrical vacuum chamber, a plurality of fixed, vertical, spaced-apart, longitudinally-extending heating coils which are constantly and firmly connected to a common supply pipe and means for guiding a plurality of vertical receptacles containing particulate food material, through the chamber and between the heating coils, said receptacles being combined, as vertically extending pockets which can be quickly filled with particulate material, into a movable structural unit which is movable between the heating devices in a comb-like manner and which is provided at both sides with rollers that run on rails mounted on the internal side of the vacuum chamber, said receptacles being pendently mounted on a portion of the structural unit that moves above the heating devices, and said receptacles having ventilator openings in the side walls, the openings being formed by baffle plates of the side walls, said baffle plates being directed outwardly and diagonally upward.

2. Apparatus according to claim 1, wherein the receptacles which extend in the vertical plane are individually movably arranged in the longitudinal direction of the chamber. 

1. A vacuum freeze-drying apparatus for particulate food material comprising a cylindrical vacuum chamber, a plurality of fixed, vertical, spaced-apart, longitudinally-extending heating coils which are constantly and firmly connected to a common supply pipe and means for guiding a plurality of vertical receptacles containing particulate food material, through the chamber and between the heating coils, said receptacles being combined, as vertically extending pockets which can be quickly filled with particulate material, into a movable structural unit which is movable between the heating devices in a comb-like manner and which is provided at both sides with rollers that run on rails mounted on the internal side of the vacuum chamber, said receptacles being pendently mounted on a portion of the structural unit that moves above the heating devices, and said receptacles having ventilator openings in the side walls, the openings being formed by baffle plates of the side walls, said baffle plates being directed outwardly and diagonally upward.
 2. Apparatus according to claim 1, wherein the receptacles which extend in the vertical plane are individually movably arranged in the longitudinal direction of the chamber. 